1. Technical Field
The present invention relates to an apparatus for applying multi-axial inertial force.
2. Description of the Related Art
Recently, as a small and light inertial sensor is easily manufactured using a micro electro mechanical system (MEMS) technology, application fields of the inertial sensor have been expanded to home appliances, etc. Therefore, in accordance with the continuous development of functions of the inertial sensor, the function of the inertial sensor has been continuously developed from a uni-axial sensor capable of detecting only an inertial force for a single axis using a single sensor to a multi-axial sensor capable of detecting an inertia force for a multi-axis of two axes or more using a single sensor.
The manufactured inertial sensor is necessarily subjected to a performance test before being released as a product. Since the inertial sensor is a transducer transducing inertial force (angular velocity, acceleration) applied to the sensor into electrical signals, performance thereof may be confirmed by applying the inertial force directly to the sensor and measuring an electrical output.
However, as the function of the inertial sensor has been expanded from the single axis to the multiple axes, a direction of inertial force that should be applied to the sensor at the time of measurement should also be increased from the single axis to the multiple axes, which causes a structure or a function of an apparatus for applying inertial force to be significantly complicated.
A tri-axial ratetable according to the prior art for this has volume three times or more larger than that of a uni-axial ratetable and is significantly more expensive than the uni-axial ratetable. Particularly, a vibration exciter used for generating linear acceleration may not generate tri-axial simultaneous vibration-excitation using a single apparatus, such that the sensor to be measured should be measured while moving the apparatus for each axis.
Due to the above-mentioned reason, a time required to test the multi-axial inertial sensor becomes significantly longer than a time required to test the uni-axial inertial sensor. An increase in test time, which is directly associated with an increase in product cost, is an important factor deteriorating competitiveness of a product.
Further, in the case of a tri-axial angular velocity sensor that may detect inertial force in three-axes directions, since characteristics thereof should be evaluated with respect to all of the three-axes directions that are orthogonal to each other, an apparatus for applying tri-axial angular velocity is required. However, the apparatus for applying tri-axial angular velocity according to the prior art has volume significantly larger than that of an apparatus for applying uni-axial angular velocity. In addition, the number of components used in the apparatus for applying tri-axial angular velocity becomes three times or more as compared to the apparatus for applying uni-axial angular velocity. In the apparatus for applying tri-axial angular velocity, an expensive and significantly precise motor is required, and significantly elaborate components such as an angle encoder that may detect a rotation amount, a slip ring connecting an electrical signal to the outside of a shaft of the motor, or the like, are used. Therefore, when the number of axes increases, components as much as a multiple of the number of increased axes are required. In addition, the slip ring serves as a channel connecting a signal output from a device under test (DUT) to an external measuring device. Since the slip ring itself becomes a noise source at the time of rotation of the motor, as the number of slip rings through which the electrical signal passes increases, a noise component of the channel increases.
Further, in the case of the vibration exciter or a linear acceleration generator, it is very difficult to generate acceleration in the multiple axes using a single apparatus. Therefore, several uni-axial vibration exciters are generally fixed and used in each axis direction. In this case, in order to perform multi-axial measurement, the DUT should be moved to and mounted on several vibration exciters set according to the directions of the axes, a test time is significantly increased, and several apparatuses for applying acceleration are required for each of the directions of the axes, such that a cost required to configure a measuring system is also increased.